AN 21 No Compromise High Throughput δ18O and δD Measurements

The ability to measure the δ¹⁸O and δD isotopic content of water has long relied on cumbersome methods that require well-equipped laboratories, highly qualified technicians and frequently calibrated instruments. The advent of commercial analyzers based on Wavelength Scanned Cavity Ringdown Spectroscopy (WS-CRDS) for isotopic water measurements has opened up new possibilities for mobile laboratory and field deployable isotopic instruments. In addition, for many of these laboratories, sample throughput has been a major bottleneck. For example, the real-time sampling of stream flow during meteorological events requires multiple samples per hour. Alternatively, the number of discrete samples gathered during a hydrology or oceanography campaign can be a daunting challenge. It is a common occurrence that a huge sample set must be analyzed within a short period of time to avoid sample spoiling. In these and other applications, the required isotopic ‘resolution’ requires a high precision, drift-free analyzer with a high throughput mode.

The solution is a Picarro water isotope analyzer which gives users the capability of 360 sample injections per day. This high throughput method comes with minimal impact on the precision and memory and absolutely no impact on the drift characteristics of the analyzer. The results shown in this study clearly confirm that the precision of the Picarro system is very high and the memory and drift characteristics are exceptional, even with a high data acquisition rate.